The benefit of lumbar pillows for encouraging proper posture while seated is relatively well known. One type of lumbar support that is currently available is a separate cushion that can be used when seated. This type of lumbar support is relatively small, typically not extending beyond the lumbar region of the spine. Lumbar supports are also built into seating such as car seats and office chairs, but generally have very small protrusions or shallow curvature.
While these lumbar supports can provide a certain level of support, they do not adequately support those with weakened cores or exaggerated spinal curvature seen especially in women who are either pregnant or who have recently given birth. During pregnancy, a woman's spine undergoes significant biomechanical changes in order to prepare for delivery. As a woman's center of gravity moves forward her pelvis tilts forward, increasing the curvature of the spine at the lower (lumbosacral) area, generally referred to as lordotic curvature. As this happens, the upper (thoracic) spine compensates by increasing its curvature, generally known as kyphodic curvature.
In addition to spinal changes in response to a shifting center of gravity, the spine is also affected by the release of a hormone relaxin that allows joints and ligaments to soften and stretch in order to aid in delivery. This affects the spine by softening the outer fibers of the intervertebral discs, reducing the rigidity of the spine and further increasing its curvature. This relaxation of the spine then relies on the supporting muscles and ligaments of the core for stability. During this time, however, the abdominal muscles are being stretched forward and cannot provide much structural support, leaving the majority of the compensation up to the muscles of the back. This generally causes tightness and discomfort as the pregnancy progresses, and continues for months after delivery as the abdominal muscles and relaxin levels return to normal. The lack of core strength is even more pronounced after a Caesarian section where the abdominal muscles have been cut.
Because of the increased curvature of the spine and decreased core strength, the weight of the upper body, especially while holding a baby during nursing, is quite difficult to counteract using primarily lower back muscles. A typical lumbar support is not very effective at providing proper support for this situation as abdominal muscles are not strong enough to cause the lumbar spine to engage the lumbar support, and the weight of the upper body, especially when holding a baby, is not significantly relieved by the structure of the lumbar support.
Other back supports on the market also fall short. For example, a back support having arms that is generally used in bed or on the floor exists that allows a user to rest their arms on the arms of the support. These devices are generally plush pillows providing a comfortable seating position, but offer little or no actual support for the spine. Pushing against the arm supports with one's elbows will generally cause the pillow to deform instead of providing a bearing surface to adjust one's posture. Even if posture is able to be adjusted slightly, the plush backing does not encourage proper spinal curvature. Some cushions such as this may add a stiff frame of some sort to provide more structure, but are often large and cumbersome to move around, and which also are too flimsy to be load-bearing.